Numbers 26:19
The descendants of Judah originally included Er and Onan, though Er and Onan died in the land of Canaan.
Genesis 46:12
and Judah's sons Er, Onan, Shelah, Perez, and Zerah. (Technically, Er and Onan had died in the land of Canaan.) Perez's sons were Hezron and Hamul.
Genesis 38:1-10
Right about then, Judah left his brothers and went to live with an Adullamite man named Hirah.
1 Chronicles 2:3-8
Judah's three sons Er, Onan, and Shelah were born to him through Bath-shua, a Canaanite. Er, Judah's firstborn, became wicked in the LORD's sight, so he put him to death.